Large Deformation Crash Analysis And Structure Optimization Of A Subway Train

With the accelerated urbanization and the scientific and technological progress, China enters a new period of development for railway vehicles. Because of the constant improvement of the railway vehicles'performance level and the substantial increase of the vehicles'speed, the security issues of impact are becoming more and more important, therefore, solving crash safety issues of the railway vehicle has become imperative. In this paper, based on one kind of metro vehicle, the impact acceleration, impact force, impact deformation and a series of data were acquired using PAM-CRASH, the structure optimization were operated applying HyperMesh and SiPESC.OPT, so as to enhance the body strength as well as energy absorption and to realize the passive safety protection and crashworthiness optimization design of the vehicle.First, the mid-surface of the body structure was extracted using Hypermesh,and a complete 3-D midsurface model was established that was required by the finite element analysis. According to the drawings describing the welding relationship between various parts of the metro vehicle, welding spots were created in 3-D midsurface model of the body, beam elements were used in Hypermesh to connect welding spots to simulate the welding relationship, the 3-D midsurface model was divided into finite elements, to ensure the accuracy of calculation,the model was mainly composed of arbitrary four-node shell elements, supplemented by three-node shell element.Secondly, the finite element analysis of the eight marshalling trains'collision with large deformation are proceeded in the PAM-CRASH, the result data of speed, acceleration, collision energy, impact force and deformation at different times was extracted. In order to verify the accuracy of the deformation, the first vehicle's collision was re-simulated, by the comparison between the simulated collision results of the single first vehicle and the eight marshalling trains, the rationality of the body's deformation was checked.Thirdly, in the finite element model of the first metro vehicle, the cab area was extracted to be optimized, so as to lower body stress and displacement under external loads.First, the initial value of body stress and displacement are obtained through static strength analysis of the model; Secondly, to optimize the structure's size, the minimum of the mass of the model was the objective function of optimization, and lower level of the stress and displacement were constraints with reference to the initial value stress and the displacement, and the plate thickness in each group of the model was the design variables for size optimization.Finally, the SiPESC.OPT system was used to optimize the structural of the first metro vehicle in order to improve the absorption effect. First, the finite element model of he first metro vehicle was simplified, because the collision energy-absorbing area is mainly the cab, so the cab area at the front of the first vehicle was kept as the same as the original structure, other regions were simplified in accordance with the principle of equivalent stiffness. The plate thickness in each group of the model was set as the design variables for size optimization and mass as the goal of minimizing, to optimize the structural of the simplified model with the purpose of improving the absorption effect, in order to achieve maximum absorption of kinetic energy and to ensure the safety of passengers in the event of a collision.